DESCRIPTION: These studies will employ specific methods for generation of hydroxyl radicals, hydroperoxyl radicals (and superoxide), and peroxyl radicals to examine the reactions of these three species with DNA. The first specific aim will examine the reactions of specific oxidants with oxynucleosides, homooligodeoxynucleotides, and homooligodeoxynucleotide complexes. Products will be analyzed by GC-MS and HPLC with electrochemical detection. The second specific aim will examine the mechanisms by which the oxidants cleave the DNA backbone by oxidizing the deoxyribose moiety. Specific products indicative of the site of radical attack will be identified. This aim also will investigate the sequence specificity of DNA oxidation by oxidants in specific fragments of a Bluescript plasmid. The third specific aim will investigate the effects of metals, organic hydroperoxides, and nitric oxide on the nature and distribution of products formed in deoxynucleosides, oligodeoxynucleotides, and DNA fragments. The proposed studies will identify marker products for oxidant-specific DNA damage and provide broader insights into the roles of oxidants in disease.